The present invention is related to sound systems for vehicles and is particularly directed to an acoustic chamber integrated into a door of a vehicle.
The earliest sound systems for motor vehicles typically included one or more loudspeakers mounted in a vehicle""s instrument panel. In these systems, the sound generated by the loudspeakers was deflected off the windshield and into the passenger compartment toward vehicle occupants. Later sound systems included loudspeakers mounted atop a shelf located behind the rear seat of a vehicle, whereby the rear window of the vehicle directed sound into the passenger compartment. U.S. Pat. No. 4,728,143 to Tanino et al. is directed to overcoming problems associated with rear-shelf mounted loudspeakers by mounting one or more loudspeakers in a side door of a vehicle. In one embodiment of Tanino, an acoustic chamber and speaker are mounted within a vehicle door, whereby the speaker diaphragm is near the periphery of the acoustic chamber and in close proximity to the door trim panel.
U.S. Pat. No. 5,218,175 to Scarlata discloses a sound system for a vehicle that includes an elongated resonance chamber located outside the passenger compartment that resonates sound at lower frequencies than those generated by a speaker. The speaker is installed at one end of the elongated resonance chamber so that the air mass within the chamber is in front of the speaker diaphragm.
The latest sound systems include loudspeakers mounted in the side doors of vehicles. These door-mounted systems save valuable space within the passenger compartment and direct the sound at vehicle occupants. For example, U.S. Pat. No. 5,663,534 to Von Hagen discloses a sound system whereby a wall of a metal bodyshell part forms a part of a speaker housing. The wall of the metal bodyshell part includes an indentation that forms a rear half of the speaker housing. The speaker housing also includes a plastic half shell that holds the speaker. The plastic half shell has a reverse-shaped bulge that mirrors the indentation formed in the wall of the bodyshell part. A sealing strip is provided between the wall of the bodyshell part and the half shell for defining a closed resonance space for the speaker. There are a number of problems associated with the ""534 patent. First, the metal bodyshell part that forms a rear part of the speaker housing is inappropriate for an acoustic environment. As a result, the sound quality of the system may suffer from transmission loss, frequency absorption and reflection. Second, the sound system of the ""534 patent cannot be pre-tested before installation into a vehicle. Moreover, the system has extra components, such as the half-shell adding weight to the vehicle and providing little room for other door-mounted components such as a window lift system.
Thus, there is a need for an improved sound system for vehicles. For example, it would be desirable to provide a sound system including an acoustic chamber that can be tested before the system is actually installed in a vehicle. It would also be desirable to provide a sound system that is light-weight, easy to assemble, and has less parts.
Certain preferred embodiments of the present invention disclose an acoustic chamber for a loudspeaker, such as a stereo loudspeaker. The acoustic chamber is preferably integrated with a door of a vehicle having a passenger compartment. The door preferably includes a door inner panel having an aperture extending therethrough and a door outer panel that defines an exterior surface of the vehicle. The door inner panel and door outer panel are preferably made of metal, such as sheet metal, and are desirably permanently secured to one another, such as by welding the panels together. The acoustic chamber also desirably includes a door module, preferably made of a thermoplastic polymer or fibrous material, secured in the aperture of the door inner panel. The door module may include one or more control elements or control circuits mounted thereto such as elements for controlling a window, side-view mirror, seat adjustment, etc . . . . In preferred embodiments, the door module includes an indentation having a concave surface facing toward the passenger compartment of the vehicle.
An interior door trim panel is preferably secured over the door module. The acoustic chamber is desirably formed by providing a sealing element, such as a compliant sealing strip, between the door module and the interior door trim panel. In certain embodiments, the interior door trim panel may include a bulge that extends into the passenger compartment. The bulge may serve as an arm rest. In these embodiments, when the interior door trim panel is secured over the door module, the bulge is preferably in substantial alignment with the indentation and the sealing element desirably extends around outer perimeters of the indentation of the door module and the bulge of the interior door trim panel. The bulge in the interior door trim panel preferably defines a convex surface facing the passenger compartment of the vehicle.
The sound system desirably has a loudspeaker secured between the door module and the interior door trim panel. In other words, the loudspeaker is preferably secured within the acoustic chamber. In highly preferred embodiments, the speaker is secured in the indentation of the door module so that the diaphragm of the speaker faces toward the passenger compartment and the backside of the speaker faces the concave surface of the indentation. As a result, the acoustic chamber lies substantially between the back side of the speaker and the concave surface of the indentation so that most, if not all of the air mass within the acoustic chamber is behind the diaphragm of the speaker.
Although the present invention is not limited by any particular theory of operation, it is believed that the above-described arrangement allows a smaller loudspeaker to be used while providing satisfactory sound quality and performance at a lower cost. The above-identified benefits are obtainable because the loudspeaker is positioned within the acoustic chamber, with a large percentage of the mass of air within the acoustic chamber being located behind the diaphragm of the speaker. As a result, the sound system of the present invention takes up less space in the door of the vehicle so that the thickness of the door may be reduced.
The use of a smaller loudspeaker also reduces the weight of the vehicle, thereby improving fuel economy and handling. The present invention also provides a dramatic improvement in sound quality over the ""534 patent to Von Hagen. The ""534 patent uses a metal bodyshell part to form a part of a speaker housing, the metal part having poor acoustical qualities. The present invention does not use a metal part to form a portion of a speaker housing. The present invention also does not use a part of a vehicle bodyshell to form a speaker housing. Instead, the present invention uses a door module and interior door trim panel to form an acoustic chamber for a loudspeaker.
In another preferred embodiment of the present invention, a vehicle door having a built-in acoustic chamber includes a door outer panel and a door inner panel connected to one another, such as by welding or riveting. The door inner and outer panels are typically made of metal. The door inner panel desirably has an aperture extending therethrough, with a door module, preferably made of a plastic or fibrous material, at least partially secured within the aperture. The door module may include an indentation having a concave surface. When the door module is secured over the door inner panel, the indentation preferably faces toward a passenger compartment of a vehicle. The vehicle door also preferably includes a loudspeaker secured between the door module and the interior door trim panel. The loudspeaker may be at least partially secured within the indentation of the door module.
An interior door trim panel may be secured over the door module. The interior door trim panel preferably includes a bulge extending into the passenger compartment, the bulge of the interior door trim panel desirably opposing and/or being in substantial alignment with the indentation in the door module. A sealing element, such as a compliant sealing strip, may be secured between the door module and the interior door trim panel for forming an air-tight acoustic chamber integrated with the vehicle door. The loudspeaker is preferably secured within the acoustic chamber, the loudspeaker diaphragm desirably facing toward the interior door trim panel and the rear side of the speaker facing toward the indentation of the door module. In preferred embodiments, most of the air mass within the acoustic chamber is located behind the diaphragm of the speaker, i.e. between the rear side of the speaker and the indentation of the door module.
In yet another preferred embodiment of the present invention, an acoustic chamber and loudspeaker integrated with a vehicle door includes a door inner panel, preferably made of metal, having an aperture extending therethrough, and a door module secured to the door inner panel. The door module is preferably at least partially positioned within the aperture of the door inner panel. The door module preferably includes an indentation, and the loudspeaker may be secured within the indentation so that the diaphragm of the speaker faces away from the concave surface of the indentation. An interior door trim panel desirably overlies the door module. A sealing element, such as a compliant sealing strip, preferably extends between the door module and the interior door trim panel, the sealing element forming an acoustic chamber between the door module and the interior door trim panel. The door module may have one or more control devices mounted thereto that are desirably interconnected with functional elements of a vehicle (e.g. an electrically controlled side-view mirror). The one or more control devices may be movable for manipulating the functional elements.
In certain preferred embodiments, the interior door trim panel may include an opening is covered by a speaker grill. After the interior door trim panel is secured over the door, the opening may be in substantial alignment with the diaphragm of the speaker so that the speaker grill substantially overlies the diaphragm of the loudspeaker. In certain preferred embodiments, at least a portion of the speaker grill engages at least a portion of the diaphragm of the loudspeaker. In particular preferred embodiments, the speaker grill is flexible so that it may substantially conform to the diaphragm of the loudspeaker.
These and other preferred embodiments of the present invention will be described in more detail below.